Apparatus for activating thermoplastic cement



Aug. l2, 1941. J. WJP'RATT ETAL 2,252,030

' 2 APPARATUS FOR GTITATING THERMOPLASTIC CEMENT FiledNov. 21 '1938 4sheets-sheet 1 l Tg Aug- 12, 1941' J. W. PRATT ETAL 2,252,030

APPARATUS FOR ACTIVATING THERMOPLASTIC CEMENT Filed Nov. 21, 1938 4Sheets-Sheet 2 Aug. 12, 1941. J. w. PRATT ErAL APPARATUS FOR ACTIVATINGTHERMOPLASTIC CEMENT Filed NOV. 2l, 1938 l4 Sheets-Sheet 3 Aug.12,1941.y J. w. PRATT mL Ps2-,030

APPARATUS FOR ACTIVATING THERMOPLASTIC CEMENT Filed Nov. 2l, 19384'Sheets-Sheet 4 y Fig". 5.

i burners ers Patented Aug. 12, 1941 APPARATUS FOR ACTIVATING THERMO- IPLASTIC CEMENT John William Pratt and Hubert Boothroyd, Leicester,England, assigner to United Shoe Machinery Corporation, Borough ofFlemington, N. J., a corporation of New Jersey Application November 21,1938, Serial No. 241,622

In Great Britain December 7, 1937 20 Claims.

This invention relates to improvements in apparatus for activatingadhesive for securing shoe parts together. The `apparatus is hereinshown by way of example as adapted for the heat-activation ofthermoplastic cement upon shoe soles prior to their being pressed uponthe shoes to effeet attachment thereto.

In the operation of sole laying as usuallyl practised, a rubber cementis applied to the shoeand sole or, in some cases, to the sole only and,after the cement has reached a suitable tacky condition, the sole islocated upon the shoe and placed in the sole laying machine. It has alsobeen proposed to use a thermoplastic cement applied to the sole andtheshoe bottom or to the sole only, the cement on the sole being activatedby heat and the shoe and sole pressed -together in a sole layingmachine.

Objects of this invention are to provide an improved apparatus foractivating thermoplastic cement whereby quick setting or cooling of thecement is facilitated and to provide convenient and effective apparatusfor this purpose.

The novel apparatus for heat-activating the thermoplastic on the part tobe united, for example upon the sole, consists in means for subjectingthe adhesive coating to intense heat for a short period, as for exampleby bringing ame into contact with the cement, so that while, on the onehand, the coating is adequately activated, yet, on the other hand, thecoated part is not bodily raised in temperature to any substantialdegree. Under these conditions, of course, the activated coating willcoolmuch more rapidly than it would if the part to which it was appliedWereheated bodily to a substantial degree.

The` apparatus further comprises, as illustrated herein, means, forexample a grid, 4to support the article to which cement has been appliedwith its cemented face lowermost, that is, against the grid, a heatingdevice beneath and at one side of the grid, and means for Vmoving thegrid andV jheating device relatively to cause the heating device totraverse the cemented surface at a pre- Idetermined rate, whereby thecement coating is activated without substantially raising thetemperat'urey of the body to which the cement has been applied. Asillustrated, a series of gas burners are made to pass beneath astationary grid, with the llames of the burners in contact Preferablythe apparatus is so arranged that'upon depression of a. treadle theburner moves slowly beneath the grid in one direction and upon a seconddepression ofthe treadle the burner moves beneath the grid at the samerate in the opposite direction. When no heat is being utilized theburners are automatically turned down.

These and other features of the invention will appear more fully fromthe following detailed description when read in connection with theaccompanying drawings and will be pointed out in the appended claims. Inthe drawings,

Fig. 1 is an elevation of the left-hand side of theapparatus for heatactivation of cement-on the sole showing the parts in their initialpositions;

Fig. 2 is a similar view showing the parts in the positions they assumeduring the traverse of the heating device beneath the grid from right toleft;

, Fig. 3 is a; detail inl elevation of the mechanism for operating theheating device with the parts in thepositions they assume after thetreadle is depressed and before it is released;

Fig. 4 is a transverse section through the grid and heating device; v

Fig. 5 is a plan view of the grid; an

Fig. 6 is a front elevation of the apparatus.

A thermoplastic adhesive which has been found satisfactory for use inone-way sole laying, that is, where the cement is applied to the soleonly, has the following formula, the proportions being taken by weight:

The composition is conveniently prepared by heating together in asuitable vessel the latex and part of the rosin (which is preferablypowdered).

with the cement, by means of appull the action of which is delayed tocause slow passage of the beneath the grid. The grid and burnlareadjustable to adapt them to conform to the shape of a molded korconformed sole.

On heating carefully to about 330 F., the water content of the latexwill be driven off and the rubber and rosin will be intimatelyassociated or digested. The remainder of the rosin may bev added to themolten mass and then portions of the China-wood oil and gutta percha.Preferably the composition is allowed to cool between the additions andis reheated prior to each addition. The beta naphthol may be added atthe last stage. This composition contains 'a relatively large proportionof the China-wood oil which has the'eifect of lowering the temperatureat now be described, referring rst to Figs. 1, 4

and 5. The apparatus comprises a base 90 from which two uprights 92, 94extend. To the upper end portions of the uprights 92, 94 are secured twobrackets 96, 98, one on each side, each bracket having at its upper enda horizontal pivot to each of which one-half of the grid is pivoted.Each half of the grid comprises a U-shaped frame |02 between the legs ofwhich parallel wires |04 extend, each grid frame |02 being provided witha pair of ears |06 for the pivot |00. The pivots |00 extend from frontto rear of the apparatus and each is adapted frictionally to retain inplace the half of the grid pivoted to it. When the two halves of thegrid are horizontal (Fig. 5) they form together a substantiallycontinuous grid and, if desired, the adjacent ends of the two `halves ofthe grid may be lifted more or less,

as shown in Fig. 4, to adapt the grid for supporting a molded orconformed sole S, each of the two halves of the grid being movable aboutits pivot I 00 by applying sufficient force thereto. Each grid, as shownin Fig. 1, has an upward convexity from front to rear, the center ofcurvature of the grid being located substantially at the axis aboutwhich the heating device (to be described) moves.

Fixed to the base 90 between the uprights 92 and 94 (Fig. 6) are twobrackets |08 having bearings in which is journaled a horizontal tube II0 the right-hand portion of which extends through an aperture in theupright 94. Extending upwardly from the tube ||0 between the brackets|08 is a second tube ||2 which joins at its upper end a third tube I I4which is horizontal. To each end portion of the tube II4 is pivoted at||5 a piece of pipe ||6 plugged at its inner end, having a series ofperforations I I8 on its upper side and provided with an air inlet |20near its outer end. Each pipe II6, therefore, constitutes a series ofBunsen burners the flames of which will be directed toward the grid. Theperforations I I8 are close enough together so that a substantiallycontinuous linear 'flame is formed. Gas is furnished to the burners ||6by connecting the tube ||0 to a source of supply, the gas beingcontrolled by a cock |22. The burners I| 6 extend underneath the grid|04 in a direction from right to left and may be swung about the axis ofthe tube ||0 to cause the contiguous Bunsen flames under the grid totraverse the grid from one side thereof to the other to activate thecoating on the sole S positioned on the grid with its cement face downand its longitudinal axis extending in a direction from right to left.Each of the burners I|6y may be adjusted about its pivot |I5 to cause itto lie substantially parallel to the half of the grid which overlies it.Preferably the burners I I6 overlap each other to some extent at theirinner ends so that when they are adjusted as shown in Fig. 4 there willbe no space between the ends of the burners and therefore the contigultyof the burners and flames will not Ibe broken.

in turn, is pivoted at |35 to the rear arm |35 of v an operating leverfixed to a rockshaft |38 joui'- naled in brackets |40 secured to thebase 90. The upper end of the link |34 has a short slot |42 to receivethe pivot pin |32 in the arm |30. The operating lever has a forward arm|44 which is connected by a chain |46 to a treadle lever |48 operated bya treadle |50 (Fig. 1). Fixed to the rockshaft |38 and upwardlyextending therefrom are two arms |52, |54. The arm |52 has a pluralityof notches |56 in its forward edge and the front end of a spring |58 ishooked in one or another of the notches |56, the rear end of the springbeing anchored to a hook |60 on the base 90.

-The arm |54 carries a pin |62 which engages aslot I 64 in the forwardend of a rod |56 connected to the piston of a dash-pot the cylinder |68of which is pivoted at |10 to the base 90, the Y arrangement being suchthat the forward movement Vof the rod |66 with respect to the cylinder|68 is not resisted but rearward movement of the rod |66 is made to takeplace slowly at a predetermined slow rate which is dependent upon theadjustment of the spring |58 along the armv The arm |26 which is fixedto the extension |24 l Y yond the rear end of the grid. That is, theburners in either of their limited positions will be beyond the gridVand there will be no heating of the grids when the machine is standingidle with the burners lit.

The arm |30 has two stop surfaces |18, |80 which cooperate with a pin|82 on the arm |26 to limit in both directions rotation of the arm |30about its pivot |28. Midway of the arm I 30 is a pin |84 to which oneend of a long tension spring |86 is connected, the other end of thespring being attached to a pin |88 iixed to the bracket 86. The weightof the burners is preferably counterbalanced by a weight |90 connectedto the -pipe I|0 on the side opposite the burners.

The operation of the above-described mechanism is as follows: When, withthe parts in the positions shown in Fig. 1, the treadle |50 isdepressed, `the operating lever |36, |44 and the arms |52, |54 are allturned clockwise with the rockshaft |38. This movement tensions thespring |58 and withdraws the piston rod 66 of the dash-pot |68. The link|34 also moves upwardly, turning the arm |30 about its center |28. Theparts assume iinally the position shown in Fig. 3,

movement of the lever arm |44 having been straight line. When theyapproachfthat. position, however, the spring |88 acts to throw the arm|30 suiliciently toward the lett, as shown in Fig. 3, so that thepivots|35 and |32 are out of line with the pivot |28, the parts being able to2oz, zu threaded through intm'ned ends ore assume this positionbyvreason of the pin-andr slot connection |82, |42, whereupon thetreadle is released. The downward pull of the link |34, due to .thereaction of the spring |58, will turn the arm |30 about its pivot |28until the surface |18 engages a pin |82, this position oi the arm beingshown in Fig. 2. .The arm |30 can assume the position shown in Fig. 2before control oi the movement is-assumed by the dash-pot because itoccurs before the pin |62 reaches the end of the arm |30, turn theburners slowly about the axis |24 until the lug |14 engages the pin |16,in which position the burners ||6 will be beyond the rear end of thegrid |02- and will come to rest in that 2 position. During the passageof the burners under the sole, each portion of the cemented area thereofis subjected to intense heat for-a short time, byv direct contact of thellames with the cement as illustrated in Fig. 4, which time will be thesame for a given setting of the machine, and the entire lcemented areais activated without subjecting any portion of the body oi the sole tothe action of the llames long enough to raise substantially thetemperature of the sole as a whole, there being thus no substantialstorage of heat. in the sole to retard the setting of the cement afterthe sole is applied to the shoe bottom. When the treadle is againdepressed the spring |58 is again placed under tension and the pistonrod |66 of the dash-pot withdrawn while at the same time the movement ofthe lever arm |36, through the link |34, turns the arm |30` clockwiseuntil the pivots |35, |28 and |32 are again in a straight line,whereupon the spring |86 will throw the arm |30 farther clockwise tobring the pivots |32, |35 to the right of the pivot |24 so that when thetreadle is released the pull of the link |34 will turn the arm |30clockwise until the face |80 on the arm |30 engages the pin |82 andfurther movement of the lever arm |36, due to the action of the spring|56, will swing the burn ers to the right until the parts assume theinitial position shown in Fig. 1.

In order to economize the consumption of gas when the burners are ineither of their limiting positions, means is provided for turning downthe gas llames of the burners when they reach either of the two limitingpositions and for turning up the flames when the burners move away. fromeither of those positions. A gas cock |84 is provided in the tube lwhich has an L-shaped vbar ilxed to the handle thereof, the barcomprising arms |96, |98, the arm |96 extending horizontally and the arm|98'extending upwardly and at an inclination toward the rightas shown inFig. 6. A spring 200 connected between the extremity. of the arm |96 andthe tube |`|2 acts, when unopposed. to hold the cock |94 in fully openposition and the spring is allowed to hold the cock in this position-while the burners are slot |64 and begins to push upon the piston rodbracket 206 secured to the upright 84 (Fig. 1). When the burners areswung toward the inoperative position shown in Fig. 1, the arm |88engages the stop screw 202 and turns the cock against the tension oithevspring 200 to turn down the 'gas ilames of the burners ||6. When theburners are swungl away from the position shown in Fig. 1, the spring200 actsto iully open the gas cockI |94, in which position it remainsuntil the burners ||6 are approaching their opposite limiting position,whereupon the arm |88 engages the stop screw 204 and again partiallycloses the cock |84 against the tension oi the spring 200. The burnerstherefore burn only with a small ame when standing idle at either limitoi their travel and are automatically turned up during their traverseunder the grids |02 by the action of the spring 200. The extent to whichthe tube `|84 is turned to reduce the flames may be varied by adjustingthe stop screws 202, 204.

In using the apparatus for activating thermoplastic cement upon anarticle, the article, for example a sole S, is placed upon the grid,preferably with its longitudinal axis extending in the direction of theburners I6 and with its cemented face in contact with the grid wires|04. The treadle |50 is then depressed and the mechanism operates asdescribedto swing the burners from either limiting position in whichthey happen to be to the other limiting position at a slow ratedetermined by the dash-pot |68, the burners during the traverse underthe sole serving to activate the cement thereon without substantiallyheating the body ofthe sole. The activated sole would be immediatelylocated upon the shoe bottom and the shoe placed in a sole press havingat least two heads, suchy as that disclosed in United states LettersPet-.ent No. 1,549,243, granted August 11, 1925, upon application of E.E. Winkley,

e which may be provided with the improved pad traveling under the grid.lAs the burners apand pad box disclosed in United States Letters PatentNo. 2,018,808, granted October 24, 1935,

upon application of Fred Ricks. Since .the body of the sole Yis notsubstantially heated, the activated cement quickly cools suiiciently toovercome the reactive tendency of the sole to separate fromthe shoe andhence, by the time the cement on another sole has been activated, thesole applied to a shoe and placed under pressure in the other side ofthe machine, the cement on the first shoe has sufllciently set so thatit can safely be removed.

Having thus described our invention, what we claim as new and desire tosecure by Letters Patent of the United States is:

1. In apparatus for heat-activating cement, a grid to support an articleto which thermoplastic cementA has been applied, a heating devicearranged to move to and fro past the grid, means for causing saidheating device to move past the grid in each direction, and a singledash-pot arranged to control the rate of movement ofthe heating devicerst in one direction and lthen in the other.

2. In apparatus for heat-activating cement, a grid to support an articleto which thermoplastic cement has been applied, a heating devicearranged to move to and fro past the grid, a spring means for varyingsaid predetermined rate.y

3. In apparatusfor'heat-activating cement, a

grid for supporting a cemented article with the cemented face toward thegrid, a heating device movable 'wto and fro beneath the grid, a springfor causing the heating device to move beneath the grid, and a dash-potfor controlling the movement 'of said heating device in response to saidspring.

4.`In apparatus for heat-activating cement, a grid to support the faceof an article to which thermoplastic cement has been applied, a heatingdevice arranged at one side of the grid, a spring for relatively movingthe heating device and the grid, and a dash-pot opposing the spring tocause the relative movement to take place at a predetermined rate and tocause the thermoplastic cement to be activated without substantiallyheating the body of the article.

5 In apparatus for heat-activating thermoplastic cement, a grid forsupporting a cemented article with the cemented face toward the grid, aheating device movable to and fro beneath the grid, a spring for causingthe heating device to move beneath the grid, a dash-pot for controllingthe movement of said heating device in response to said spring, meansfor varying the mechanical advantage of the spring over the dash-pot,and a treadle for tensioning the spring and setting the dash-pot.

6. In apparatus for heat-activating cement, a

horizontal grid to support cemented side down an article to whichthermoplastic cement has been applied, a heating device arranged at oneside of the grid, spring means for moving the heating device laterallybeneath the grid, and a dash-pot arranged to cause the heating device tomove at a predetermined rate to cause the thermoplastic cement exposedthrough the grid to be activated without substantially heating the bodyof the article.

7. In apparatus for heat-activating thermoplastic cement, a grid forsupporting a cemented article with the cemented face toward the grid, aheating device movable to and fro beneath the grid, a spring for causingthe heating device to move beneath the grid, a dash-pot for controllingthe movement of said heating device in response to said spring, and'atreadle for tensioning the spring.

8. In apparatus for heat-activating thermoplastic cement, a grid adaptedto support acemented sole in a horizontal position, a linear heatingelement extending lengthwise of the sole and arranged to travel past thecemented. face of the sole, a spring for causing said heating element totravel from side to side of the sole, and a dashpot arranged to causesaid travel to take place at a predetermined slow rate progressively toactivate the cement from one lateral extremity of the sole to the other.

9. In apparatus for activating thermoplastic cement, an arcuate grid forsupporting the cemented face of an article, a heating device movable toand'fro beneath the grid about the center of curvature of the grid, aspring for causing the heating device to swing upon its pivot, means fortensioning the spring, and means for causing the spring to swing theheating device rst in one direction and then in the other.

10. In apparatus for heat-activating thermoplastic cement, a horizontalgrid for-supporting a cemented sole with its cemented face in contactwith the grid, a heating element arranged tol travel beneath thecemented yface of the sole in proximity to the cement, means comprisinga spring and a dash-pot for causing said heating element to travelbeneath the sole at a predetermined ,slow rate progressively to activatethe cement from one extremity of the sole to the other,

' and means for causing said spring and dash-pot to move the heatingelement beneath the sole in the opposite direction to activate the sameor another sole. l

11. In apparatus for activating thermoplastic cement, an arcuate gridfor supporting the cemented face of an article, a heating device movableto and fro beneath the grid about the center of curvature of the grid, aspring for causing the heating device to swing upon its pivot, a dashpotto control movement of the heating device in response to the pull of thespring, means for tensioning the spring, and means for causing thespring and dash-pot to swing the heating device and control its rate ofmovement iirst in one direction and then in the other.

12. In apparatus for heat-activating thermoplastic cement, a grid, asupport mounted to swing to and fro beneath the grid, a heating devicecarried by the support, a lever, a treadle for operating the lever, aspring connected to the lever so as to be tensioned .when the treadle isoperated, a dash-pot connected to the lever to oppose the action of thespring and cause the lever to be operated slowly by the spring when thetreadle is released, and connections f rom said lever to the support tocause the support to be swung in one direction upon release of thetreadle and upon depression and release of the treadle a second time tocause the support to be swung in the opposite direction.

13. In apparatus for heat-activating thermoplastic cement, a grid, asupport mounted to swing to and fro beneath the grid, a heating devicecarried by the support, a lever, a treadle for operating the lever, aspring connected to the lever so as to be tensioned when the treadle isoperated, a dash-pot connected to the lever to oppose the action of thespring and cause the lever to be operated slowly by the spring when thetreadle is released, and connections from said lever to the support tocause the support to be swung first in one direction and then in theother upon successive operations and releases of the treadle.

14. In apparatus for heat-activating thermoplastic cement, an arcuategrid for supporting a sole with its cemented face in contact with thegrid, a support pivoted below the grid to swing about the center ofcurvature of the grid, heating means carried by the Support, stops 4forlimiting the movement of the support so that in the limiting positionsthe heating means will be beyond the grid, a treadle-operated lever, aspring connected to the lever so as to be tensioned when the treadle isdepressed and to tend to return the lever to initial position when thetreadle is released, a dash-pot connected to the lever so as to be setby depression of the treadle and to control movement of the lever inresponse to the spring when the treadle is released, an arm pivoted formovement bodily with the support and to swing with respect to thesupport between two limiting-positions, the end of the arm being in onelimiting position on one side of the pivot of the support and in theother limiting position on the other side of the pivot of the support, alink connecting the end of said arm to the treadle-actuated lever, andmeans acting when the treadle is released to cause the arm to be thrownfrom one toA the other of its limiting positions,

15. In apparatus for heat-activating cement, a grid adapted to supportthe cemented area of a sole, the grid being in two parts supported onseparate pivots whereby the two parts may,

be positioned in the same plane to support a flat sole and the parts maybe inclined to each other to support a molded or conformed sole, `and aheating device arranged to pass to and iro beneath the grid to activatethe cement on the sole.

to support a molded or conformed sole, and a pair of tubular gas burnersarranged beneath the grid, said burners overlapping at their inner endsand being pivoted at their outer ends to permit them to be arrangedparallel to the grid in its various adjusted positions.

17. In apparatus for heat-activating cement,

a grid adapted to support the cemented area of a sole, the grid being intwo parts, one side of each being adjacent to one side of the other andeach at the opposite side being pivoted to a fixed support whereby thetwo parts may be positioned in the same plane to support a iiat sole andthe parts may be inclined to each other to support a molded or conformedsole, and a heating device arranged to pass to and fro beneath the gridto activate the cement on the sole.

18. In apparatus for heat-activating cement,

a grid adapted to support the cemented area of a sole, the grid being'intwo parts supported on separate pivots whereby the two parts may bepositioned in .the same plane to support a ilat sole and the parts maybe inclined to each other to support a molded or conformed sole, and apair of tubular linear gas burners arranged beneath the grid and pivotedat their ends to permit them to be arranged parallel to thev grid in itsvarious adjusted positions.

19. In apparatus for heat-activating thermoplastic cement, a support toreceive the cemented face of an article, a heating device arranged tomove from an inoperative position at one side of the support to aninoperative position on the opposite side of the support, means forreducing the energy expended by the heating device when the device is ineither of its inoperative positions, and means for increasing the energyconsumption of the device while it is moving from one inoperativeposition to the other.

20. In apparatus for heat-activating thermo-y plastic cement, a supportto receive the cemented face of an article, a gas burner located beneaththe support and arranged to move beneath the support from an inoperativeposition at one side of the support to an inoperative position on theother side of the support, and means for reducing the gas supplied tothe burner when in either of its inoperative positions and forincreasing said supply while the burner is in transit from oneinoperative position to the other.

JOHN WILLIAM PRATI'. HUBERT BOOTHROYD.

